This disclosure generally relates to non-destructive inspection (NDI) of structures and more particularly relates to non-destructive detection of defects in a structure using thermographic image data.
Non-destructive inspection of structures involves thoroughly examining a structure without harming the structure or requiring significant disassembly. Inspection may be performed during manufacturing of a structure and/or after a structure has been put in service to determine the condition, quality, or structural state of the structure.
The production manufacturing of large composite structures for an active airplane program needs to be done at a rate that meets schedule commitments. Non-destructive inspection of primary structure is a necessary part of the manufacturing process and must be done at a rate capable of keeping up with the production schedule.
For example, it is known to fabricate barrel-shaped fuselage sections made of composite material with high through-put. The finished fuselage sections need to undergo NDI also at a high rate. Some existing solutions for inspecting barrel-shaped fuselage sections are large, expensive multiple-axis robotic systems which move ultrasonic transducer arrays over the outer mold line (OML) of the fuselage section using encoded rails and end effectors guided to follow pre-programmed paths.
Active (i.e., pulsed) thermography is another method used in the aerospace and power generation industries to nondestructively evaluate structural components for sub-surface defects. It is effective for uncovering internal bond discontinuities, delaminations, voids, inclusions, and other structural defects that are not detectable by visual inspection of the component.
There is a need for improvements in systems and methods for non-destructive inspection of large structures made of composite material to facilitate a high rate of production.